Process of fortifying and stabilizing a citrus fruit juice



Jan. 14, 1964 E. M. BYER ErAL 3,117,877

PRocEss oF FORTIFYING AND STABILIZING A CITRUS FRUIT JUICE Filed Jan. 16, 1961 2 Sheets-Sheet 1 G ..eso Rm w .323:3 2:.; -\m sw... s OB .5333. Y 1 k BNM. n e2... rz y 1 J 1mm m N t?, 83326 Se IMMM.. A f... n www. m A ISR of ...21:5 .T255 om ...du SEESSOLIJ r mw... J. A oN. zal 9. ov) \S.N \E.- 3 E m q N k `\\\\\\\\\\\\\\\\\N\\\\\\\\\\\ v\ v\v\\w\\\\ A www OS. ww o@ mu 3.83am n nu 1 mm u@ mwN mw. N M H 222.350 SuoEE vm Pm v mnu.- .u 0*.5; OITWWCOO QU ,Ar D* 1 Nmv) m mi .U m. n m. nu mo |o.-

NN M N n m 1 mw p .1- Y 3 u.. KON m i s m o o fl N E. M. BYER ET AL PROCESS OF FORTIFYING AND STABILIZING Jan. 14, 1964 A CITRUS FRUIT JUICE 2 Sheets-Sheet 2 Filed Jan. 16, 1961 wwwa@ o nomcouzooscoz IIVL ELLIS MILTON l BYER ALFRED. vALLEN LANG BY AJ-MAM- fh'nul.' MM. l 51* J 'ATTORNEYS Uite.. l

The present invention relates to improvements in the stabilization of flavor-enhanced vegetable concentrates and, more particularly, to a process for the recovery from fruit juices of volatile constituents and the incorporation thereof into concentrates characterized by their stability and acceptability throughout the period of storage.

It is an object of the present invention to provide a process whereby volatile avor fractions recovered from fruit juices, typically citrus juices, are incorporated into a juice concentrate in a condition whereby a fresh fruitlilie ilavor is provided for an unusual storage period.

A speciiic object of the invention is to provide means whereby a high yield of a desired fresh fruit davor fraction can be employed in a juice concentrate without employing complicated plant equipment.

Heretofore, it has been proposed to flavor-enhance juice concentrates by recovering most of the volatile flavor-producing constituents evaporated in the course of concentrating fruit juices. These constituents have various high and low boiling points. Thus, the art has been concerned in the past with the problems encountered in the collection of all or most of these constituents. Suggested procedures have called for condensation, absorption, or other means for separation and collection of volatile essences, including esters, alcohols, aldehydes and other organic constituents, by the employment of a wide range of temperatures and pressures. Such collection techniques may be wasteful of expensive refrigerants such as liquid nitrogen, liquid air and the like, and call for complex condensate handling means which limit the applicability of such procedures on a wide scale in the juice concentrate art. Then too, such collection techniques involve the recovery of a large quantity of low molecular weight gases such as nitrogen, carbon dioxide, oxygen and other non-condensables which have a high diffusivity creating high vapor velocities and hindering the ability to condense the desired volatile essences on a practical scale.

Others in the art have suggested procedures whereby ilavor values produced in the course of a partial evaporation of a juice are condensed at less reduced temperatures; here also, however, the prior art workers have mainly been concerned with the collection of as much as possible of these volatile constituents, including the more volatile materials and, as a consequence, have suggested the use of relatively complex packed fractionatng columns, singly or in series. Such means generally place a substantial burden upon plant investment and operation and have not been found to produce an adequate yield or quality of avoring material for use in fortication of concentrates. In the main such techniques have been concerned with the recovery of constituents which boil at temperatures lower than the boiling point of water and discarding some valuable higher boiling avoring components. Although low boiling constituents offer some fragrance reminiscent of fresh juice, they are recovered at only a relatively minor inconsequential level such that their use in large quantities on a commercial basis is impractical.

It has been discovered that a high yield of useful volatile avoring constituents can be recovered in a prachttes i@ Patented dan. i4, iSd-'fi tical concentration for subsequent use in a manner which calls for only moderately reduced working temperatures and, surprisingly, is isolated from volatile fractions heretofore discarded.

The present invention is applicable to a variety of fruit juices which range in their sensitivities to operating temperatures. The term fruit as it is employed herein and in the accompanying claims is intended to apply not only to citrus juices such as those from orange, grapefruit, tangerine, and the like, but also to non-citrus fruit juices typified by those from tomato, strawberries, boysenberries, grape, prune, apple, and the like. Indeed, the term fruit as it is employed herein and in the accompanying claims is intended to apply to plant juices generally and not be restricted to plant juices commonly classed as fruits, since many of such juices or extracts typified by the water extract or" roasted and ground coffee also contain ingredients which provide desired essences, esters, alcohol, aldehydes, and other organic constituents more or less recoverable and stabilized by the present invention. The term juices is therefore employed to include extracts, nectars, purees and, generally, plant liquids separated from plant tissue by mechanical extraction or by solution and which may contain therein food solids as well as liquids, all of which are desirably conentrated by at least partial evaporation of water therefrom.

The present invention involves the recovery of a specific davor fraction of use from volatile constituents of fruit juices and the incorporation of this fraction in a concentrated juice portion under conditions wherein the oxygen content of such juices and said flavor fraction is at an extremely low level, typically less than 0.20 ml. oxygen per 10'() gms. of juice concentrate containing the avor fraction. The maximum oxygen level specified herein uses a juice concentrate product having a Brix level of 42 as a reference point. The maximum oxygen level at other Brix levels can be readily determined by adjusting the iigures to such reference level of 42 Brix. Thus, the maximum oxygen content as deiined in the description and claims of this application is intended to cover the oxygen content at different Brix levels which correspond to 0.2() ml. per gms. of nal juice concentrate having a Brix level of 42. The specific fraction of use is recovered by:

(a) Causing the fruit juice to iiow rapidly, preferably in a thin, continuous iilm, over a heat exchange surface which is under a substantially reduced subatmospheric pressure, typically less than 1%." of mercury, in a closed system to partially concentrate the juice by separating it into a major juice concentrate portion and a minor volatile portion condensed to include flavor-producing volatile constituents boiling at temperatures higher and lower than that of water and to exclude non-condensable gaseous constituents including oxygen. The temperatures employed to effect such separation will be dependent in great measure upon the identity of the juice being processed. In the case of a citrus juice, the juice temperature generally does not exceed F. at any point in its flow over the heat exchange surface and, more ideally, the citrus juice is caused to travel at temperatures above about 40 F. and below about 80 F. However, for other juices typified by tomato, higher temperatures may be employed, say F., Where the :flavors in the juice concentrate portion as well as desired constituents separated therefrom are not as sensitive to heat;

(b) The aforesaid volatile fraction produced by the rst step is thereafter subjected to condensation continuously, at such temperatures that the volatile davor-producing constituents are collected as a two-phase oilywatery mixture. Advantageously, the temperatures at u) which this oily-watery mixture may be collected by condensation may be only moderately reduced, typically 30- 70 F. Usually, it is found that the desired condensate collected is in the neighborhood of -15 by weight of the juice initially introduced to the evaporator system or third etect vaporization chamber;

(c) The aforesaid two-phase mixture is thereafter separated into a minor subtraction containing desirable high as Awell as ,low boiling flavor-producing constituents and a major subtraction containing mainly previously condensed Water and an undesirable quantity of oily davor-producing constituents. lt is this minor subfraction which has been found to offer desirable flavor enhancement to the juice concentrate. Such separation can be carried out by azeotropic distillation of the two-phase mixture under absolute pressures of less than 11/2 of mercury at temperatures oi 50 l 00 yF. or by any other process yielding substantially the same minor subtraction, as 'will be described hereinafter. Preferably the minor subfraction is further subdivided by allowing the watery and oily phases to separate one from another upon standing, the watery phase being continuously removed from the bottom of this separation while accumulating an oil level on the surface; upon Sullicient oil accumulation, this oil is drained oil separately and subsequently mixed with a quantity of suitable high boiling organic material, ty ically cold pressed citrus oil in the case or" citrus juices, eg., cold pressed orange oil. For the purposes of the present invention it is preferred that this minor subtraction be collected by condensation in a closed system, that is one where no external vapors are introduced to the minor subtraction.

The minor subtraction of use generally represents about 0.5-1.5 by weight of the whole juice. The -speciiic subfraction of citrus juices like oranges and 4grapefruit is relatively colorless and has a light, cloudy appearance stemming from the emulsication therein of the minute quantity of oily material associated therewith, which minute quantity makes a desirable ilavor contribution. The s eciiic subtraction of use is ideally recoverable by evaporation at only moderately elevated temperatures and by condensation at temperatures ranging above 30 F. and upwardly to 70 F. when employing absolute pressures in the neighborhood of less than 11/2 in. of Hg; however, this fraction may also be condensed at temperatures below 30 F. by means of a brine solution or other refrigerating means which, depending on the temperature of condensation, may cause icing in the collection vessel and which permit recovery of the vtraction as a snow rather than liquid.

lt is a feature of the present invention that the foregoing minor subtraction of use is added to a juice concentrate under such conditions that the residual oxygen level in the packaged concentrate is less than 0.20 ml. oxygen per 100 gms. of juice concentrate at 42 Brix. It has been discovered that at such drastically reduced oxygen levels the stability of the llavor fraction of use in storage is prolonged vfor an unusual period of time. A preferred embodiment of the present invention involves the incorporation of this Volatile fruit ilavor fraction into concentrate to which raw or dilute juice commonly referred to in the citrus industry as cut-back juice has not been added; to this practice the oxygen level in a final juice concentrate having a Brix level of 42 can be reduced as low as 0.02 ml. per 100 gms. of concentrate. The total gas level in such a concentrate can be reduced to 0.10 ml. per 100 gms. of concentrate. However, it is also within the spirit of this invention that single strength fresh juice (cut-back) may be combined with the concentrate to which the fruit davor fraction has been added; in this practice oxygen levels of 0.17 ml. and less have een observed in the packaged product. This level can be materially reduced in cases Where the citrus juice or other fruit juice concentrate has cut-back juice added to it, by subjecting the cut-back juice to an oxygen-stripping operation employing an inert gas such as nitrogen to remove oxygen from the cut-back juice prior to its being blended i ith the concentrate. lu cases where the cut-back juice is not employed the juice concentrate is nevertheless protected from picltup of oxygen in subsequent operations by carrying out the concentration in multi-effect evaporators which are substantially air tight, it having been found that the conventional pumps, valves and lines to the various high vacuum evaporators may serve (unless properly sealed) to aerate concentrate with sufiicient oxygen to impair the storageability of a juice concentrate containing the specific llavor fraction of use. The presence or" even a trace quantity of oxygen, say above th level of less than 0.20 rnl. oxygen per gms. of juice concentrate at the reference Brix level of 42 will result in a noticeable deterioration of the ilavor values stemming `from the use of the specific flavor fraction of Accordingly, the various stages of the customary juice concentration operation, viz., the high vacuum evaporators, the mixing and storage tanks, and the can filling machines as Well as the lines interconnecting these stations should be designed to preclude the ingress or" oxygen into the juice.

ln the course of packaging juice concentrate with the specific ilavor fraction of use it may also be found to be desirable to take precautions that a low oxygen Containing atmosphere is present in the headspace of the can prior to sealing; such a condition can be created by the forming of a vacuum in the headspace, or by sweeping the headspace with an atmosphere of nitrogen or some other inert gas.

lt will be recalled that the foregoing process for recovering the volatile fruit ilavor fraction desired may be carried out under subatmospheric pressures at only moderately elevated temperatures in the initial whole juice concentration step; the juice concentrate portion may be subsequently introduced on either a continuous or batch basis to further heat exchange equipment wherein it may be caused to again travel in the form of a tuin over one or more heat exchange surfaces also maintained under subatmospheric pressures 'out at higher temperatures whereby the m re concentrated juices will be reduced in viscosity and thereby more effectively concentrated; in accordance with the present invention this heat exchange equipment is sealed against the possibility of ingress of atmosphere oxygen `in order that a substantially oxygenfree atmosphere may be preserved; also, it should be noted that in the course of the various concentration steps the volatiles (mainly ywater) removed and discarded subsequent to the initial whole juice concentration operation will serve to remove any entrained oxygen or carbon dioxide, the presence of which would be detrimental to ilavor stability. Although evaporation temperatures above 100 F. may be practiced in the case of some Lruit juices like grape or tomato, most `citrus juices call for moderate evaporating temperatures at least in the initial stages of concentration and, hence, it has been found useful in the present pr cess to employ highly volatile so-called refrigerant gases, typically ammonia, which when compressed contain sullicient latent as well as sensible heat to boil the desired volatile constituents as well as entrained oxygen. Since the desired flavor fraction is collectable by condensation at temperatures above 30 F., a continuous heat exchange cycle employing such refrigerant gases is ideally suited to the present pocess; thus, after the compressed re'irigerant gas has surrendered its heat to the juice or juice concentrate, it can be employed in its liquid statey to remove sensible heat as well as the heat of condensation from the distilled fraction, the heat of which can be. reused to heat the liquid refrigerant for subsequent cycles. The heat of a compressed refrigerant gas may be utilized directly to boil further quantities of juice or it may be employed indirectly through transfer to another medium such as water which could serve in boiling the juice or the concentrate. Howeer, it is not intended that the present process be restricted to the use of such refrigerant gases since steam may be introduced to the heat exchange RSC.

surface to eiect juice concentration as well as redistillation of the two-phase oily watery mixture and since cold water can be employed to condense the minor volatile portion separated from the initial concentration step as well as the redistilled volatile fraction.

For citrus juice concentration it is preferred that the non-condensables not be collected so that the redistilled condensate employed for flavor enhancement is relatively free of those materials like carbon dioxide and oxygen which impair the iiavor values of the concentrate even at temperatures below 0 C. Thus, in the case of orange and grapefruit juice it is preferred that the non-condensables and the diflicultly condensable volatile vapors be evacuated from the initial concentration of the juice in a non-oxidizing atmosphere and discarded, thereby freeing collection of the irst two-phase oilywatery mixture from interference from such non-condensables and highly volatile constituents caused by their high gas velocities and resulting in more stable juice concentrates fortiiied with the specific flavor fraction of the present invention. Iln this connection it is noteworthy that the citrus juice concentrates fortified with this avor fraction have been characterized by their improved freedom from oxidative changes and the accompanying ability to avoid use of costly nitrogen packaging. However, where storage life over an extended -period is anticipated, it has been found to be critical to stability of the citrus juice concentrate fortified with this flavor fraction that the operation be carried out in a manner which establishes a low-oxygen level in the packaged product, on the order of less than 0.2i? rnl. oxygen per lGO gms. of juice concentrate having the reference Brix level of 42.

ideally, the specific flavor fraction of use may be mixed in liquid form with the juice concentrate thereby offering the advantages of a simple plant recirculation. However, it has been found that a rather prolonged shelf life for flavor-enhanced concentrate is achieved when the specific flavor fraction of use is frozen into individual portions or pieces, typically cubes or discs, which are introduced to the juice concentrate in the can or other package just prior to freezing. lt appears that, by maintaining the speciiic tiavor fraction in a frozen condition separate from the frozen concentrate, the flavor values of die product are maintained over an unusually long period of time.

The invention will now be more `fully described by reference to the accompanying drawings. FlG. l is a schematic view of a typical plant operation for carrying out juice concentration and tiavor fraction recovery; FlG. 2 is a schematic view of the system whereby the juice concentrate and flavor fractions are combined in accordance with this invention.

Referring to EG. l, the system will be seen to cornprise a number of evaporator-s, a triple effect evaporator being shown for illustration. A compressed refrigerant gas is introduced to the triple eect evaporator to suppl* heat for `boiling orange juice indirectly through recirculated water. The present invention is not to be restricted to the modication of orange juice concentrator to be described herein since apparatus capable of employ'ng a hot compressed refrigerant gas in a direct heat exchange relationship `with boiling juices may also be ernployed7 typically the system disclosed in U5. Patent No. 2,570,210 to Joseph A. Cross issued October 9, 1951.

For the preferred oranve juice concentrator of the presen-r invention, a series of connected falling lm type evaporator umts 19A, tlB, and lilC re employed, each unit comprising a vertical tubular evaporator having a shall and a nest of tubes (not shown) which are retained by suitable upper and lower tube sheets (not shown) in the shell. in the iirst effect evaporator ltlA water is recirculated through a hot refrigerant gas condenser 2li of the shell and tube-type Where the heat of the hot gas is transferred through the walls of the tubes, water heated thereby being brought into heat exchange relationship with the tubes of evaporator unit NA by means of hot water line 2l. After the Water in the iirst effect evaporator unit ltA has been brought into heat exchange relationship with the tubes therein to elevate the juice ternperature and volatilize low and high boiling aromatic constituents therein, the water is withdrawn from the top of the evaporator through pipe 22, water being recirculated to condenser 20 by of pump 23 and pipe 24. A suitable ammonia compressor 25 communicating with ammonia condenser E@ through ammonia gas line 28 compresses ammonia vapor whereby hot ammonia gas is delivered into heat exchange relation with gas condenser 2li, condensed liquid ammonia collected in condenser 20 flowing into ammonia receiver 27 through line 29. Liquid ammonia in receiver 27 is floated on ammonia line 27A to maintain an adequate supply of liquid ammonia for level control means 27B of vapor condenser 82.

Fresh juice is supplied to evaporator unit llC through a suitable feed pipe 19, which is located to feed fresh juice at a rate sufcient to maintain the level of liquid shown in sump WBC. A ilow control valve IlZC located in pipe it? controls the rate at which fresh juice is deivered to sump 'SC and operates under the control of pneumatic level control means lSC in communication with tail pipe MC for sump mC. 1Eresh juice iiowing to third effect evaporator lilC is delivered by tail pipe MC to sump 76C above the liquid level therein so as to flash oil the vapors which pass to vapor condenser S2. The liquid in sump 76C passes through line 14C to circulator pump 42C which delivers a major portion thereof through pipe iC to the upper extremity of the third effect concentrator lili) where it flows downwardly within each of the tubes therein (not shown), the juice being distributed in the tubes by means of a header having suitably mounted therein distributor tubes, a distributor tube being mounted at the upper extremity of each heat exchange tube for assuring uniform distribution of the juice in the form of a falling iilm in positive contact with the inner walls of the tube, all of which is well known to those skilled in the art, eg., FIG. 4 of the aforesaid Cross patent. The remainder of the liquid moved by pump 42C passes through pipe 46S for evaporation in the second effect evaporator in the system diagrammed in FIG. l, the boiling juice vapors of the first evaporator unit rlA are brought into heat exchange relation through duct oil with juice being circulated to the nest of heat exchange tubes in second effect evaporator ESB, and the boiling juice vapors in second effect evaporator are delivered through duct 62 into heat exchange relationship with the nest of tubes for the third effect evaporator MC. Thus boiling juice vapors introduced to the shell surround the nest of heat exchange tubes therein and transfer their heat of liquefaction to juice traveling downwardly in contact with the inner walls of the exchange tubes in unit l'C, the concentrated juice being collected at sump 'lC in the lower extremity of evaporator ESC with the vapors introduced to the shell of evaporator unit le() being condensed therein, collected and removed from the area around the base of the heat exchange tubes through pipe 72C and delivered by vapor condensate pump id through line '75 to an ammonia subcooler generally shown at 76. Similarly, concentrated juice from the first effect evaporator lllA is collected in sump 79A. The juice vapors condensed in the second effect evaporator 131B are removed through pipe 72B and delivered through tl-shaped vapor condensate trap 78 and pipe ill? communicating with draw-off pipe 72C through the intermediation of the pool for vapor condensate around the lower extremities of the nest of heat exchange tubes inthe third effect evaporator.

ln operation fresh juice is admitted through control valve MC in pipe d@ at a rate sufficient to maintain a substantially constant level of juice in sump 70C of the third effect evaporator unit; similuly, valve 12B is adjusted to eiect a level of juice in the sump 76B of the second effect evaporator and valve 12A in line 46A maintains a suitentre?? able level of juice in sump 79A of the first effect evaporator, pneumatic level control means lSA, B and C, respectively, being employed to control the operation of valve means ZA, B and C, sensing devices for the pneumatic liquid control units being in communication with tail pipes 14A, B and C, respectively, the operation of such means being well known to those skilled in the art. Thus, through the operation of the valve means just described the rate at which fresh dilute juice and portions of concentrated juice are supplied to the individual evaporator units is controlled to provide a substantially uniform level of juice in the respective sumps of the various eects. Level control means lSC preferably feeds the juice to sump 7?C above the level of the liquid therein so as to ensure vaporization of the volatile portion of the juice. This is desirable mainly in the third effect evaporator tiC since this is where the vapors which are used to produce the specific flavor fraction of use are taken off. This type of feed can also be used in the first and second effect evaporators ilA and 1GB desired, instead of the connection shown.

A vacuum is drawn through lines QB, 93C and 99D communicating with evaporator units and 16C and vapor condenser $2, respectively. The suction drawn through lines 90B, C and D is effected by any well known steam ejection system, the design of which is well known to those skilled in the art, a three stage steam ejection system with a hogging jet being generally shown at 92.

In operation fresh dilute juice delivered to the system through pipe itl will be evaporated and concentrated through the successive stages of evaporator units GC, 1GB and 19A and eventually delivered by circulation pump 42A through product pipe 458A to additional evaporators for further concentration and subsequent combination with other juice constituents for aromatizing the juice, as will be hereinafter described; the boiling juice vapors produced in the third effect evaporator tC are removed therefrom through vapor duct 6d and delivered to a tubetype vapor condenser 82 in heat exchange relationship with the vapors, cold liquid ammonia circulating through the tubes of the condenser 32 bringing about condensation of the vapors around the tubes in condenser 82, Wherefrom the condensed vapors are collected at sump 84, delivered through pipe 85 to pump Se and pipe S8 which delivers the juice vapor condensate to means for further concentration. The juice vapors condensed in the third effect evaporator lilC and removed though pipe 72C are circulated by pump '74 through line 75 to an ammonia subcooler generally shown at 76. Liquid ammonia from receiver 27 reaches the subcooler 75 through line 27A, ammonia subcooler 76 serving to further cool liquid ammonia by having the relatively coo-ler waste condensate in line 75 brought into heat exchange relation with the liquid ammonia. Thus the temperature of ammonia circulated through line 77 and level control means 27B to vapor condenser 82 is lowered and the efficiency of the vapor condenser is increased. Heat from juice vapors in condenser 82 is transferred to the liquid ammonia, the latter being recirculated back to pump 25 as a gas through line 79 and suction line 27D.

The liquid phase recovered by the condenser 82 is essentially the vapor condensate of fresh dilute juice and is substantially free of the diicultly condensable vapors and no-n-condensable gases such as nitrogen, carbon dioxide and oxygen. This liquid phase is recovered in the course of initial concentration of fresh juice by subjecting the juice to reduced subatmospheric pressures generally dess than 11/2 of mercury absolute and ranging typically downward to about 1/2" of mercury and below; as indicated previously the vapors of fresh dilute juice are evaporated at temperatures which will not occasion degradation of the various desirable essences evaporated and generally will be at a temperature above about 70 F. and not exceed about 140 F.; the range of temperature sensitivities varying, of course, for various juices, The liquid phase contains various constituents (predominantly water) many of which boil at temperatures higher as well as lower than that of water. ln general, this liquid phase will be recovered as a minor proportion by Weight of lthe fresh juice being subjected to evaporation in the third effect evaporator 16C and, typically, in the case of citrus juice, will be in the neighborhood of 515% by weight of the fresh dilute juice.

This liquid phase is subjected to a redistillation or rectiiication to recover a desired oily-watery fraction. Thus, the liquid phase in pipe 83 is introduced to an evaporator unit wherein it is caused to travel in the form of a thin lm along a preferably elongated heat exchange surface which is in heat exchange relationship with a hot gas or liquid, typically, hot ammonia gas. One form of evaporator comprises a tube-type evaporator having a plurality of vertically arranged elongated tubes suitably nested at their upper and lower extremities and adapted to receive the liquid phase delivered thereto from pipe 5S. Preferably an evaporator of the type shown in the aforesaid Cross patent is employed, a suitable distributor pipe such as that shown in FIG. 4 of Cross being located at the upper mouth of each tube to cause the liquid phase to travel uniformly down along the inside heat exchange surface thereof. Hot ammonia gas from compressor 25 is delivered through inlet pipe 114 communicating with shell H6 surrounding the nest of tubes, hot ammonia gas being thereby placed in heat exchange relation Iwith the liquid ilms forming within the tubes and thereby br'mging about transfer of sensible heat and latent heat of evaporation to the liquid phase; hot ammonia gas condensing around the tubes is contained within and removed from the shell as a liquid through liquid ammonia pipe 1118 communicating with ammonia receiver 27. Substantially aill of the low boiling constituents (relative to the boiling point of water) together lwith certain high boiling constituents are volatilized in the tubes and conducted through duct l2@ to vapor condenser 126 wherein they are condensed. The balance of the liquid phase in the tubes which has not volatilized contains high boiling constituents which are undesirable and these materials are collected in a suitable sump generally shown as 122 and pumped as at tif/.4 to a suitable Waste. Generally the waste from the liquid phase will be a majority by Weight of the liquid phase being treated in the evaporator, typically, -95 parts by weight of the liquid phase. Condenser :126 is preferably of the tube-type and has the vapors condensed therein by means of liquid ammonia delivered thereto by line H7 from receiver 27, the liquid ammonia being fed at a temperature in the neighborhood of 30 F.; the vapors condensed around the tubes of the condenser 126 are collected as an oily-watery fraction and are removed therefrom by means of pump E39 communicating with condenser shell 132 through pipe i3d. An ammonia gas line 13S connects the shell of condenser 126 with the shell of the surge drum oi' level control means 27B wherefrom gas is recirculated through line 27D to compressor 25. A vacuum fline 14@ connects the shell of condenser 126 with vapor condenser S2 from which it derives its vacuum, the latter being under negative pressure from the vacuum system generally indicated at 92. The liquid phase entering the redistillation unit within shell 116 is subjected to a reduced absolute pressure generally between 11/2 and 1/2 of mercury and below. The temperature of the liquid phase entering the redistillation unit will typically be about 60 F. and generally should be at a temperature whereat low and high boiling constituents are maintained in the liquid phase. The temperature of the liquid phase in the redistillation unit should be above that temperature Where, at the particular pressure employed, approximately 10% of the yliquid phase will be volatilized and recovered as an oilywatery condensate fraction in condenser 126; the yield of oily-watery fraction condensate will be dependent upon a number of variables including the total area of the heat exchange surface to which the liquid phase may be exposed, the temperature on said surface, the absolute pressure existing `in the redistillation unit and the duration of exposure of the liquid phase to any particular temperature. Any volatile constituents vaporized in the course of redistirllation and not collected by condenser 125 will be circulated through vacuum pipe 140 to vapor condenser 32 whereby such vapors may be condensed and recycled to the redistillation unit.

It is a feature of the invention that the oily-watery fraction of use is combined with juice concentrate and cut-back juice in a manner which does not materially increase the oxygen content of the juice concentrate product. Referring to FIG. 2 the oily-watery fraction pumped from the redistillation unit by pump 13G is delivered through line 159 to a mixing tank 152 wherein the cutback juice and juice concentrate from pipe 48A are blended. As will be seen from FIG. 2 the blend tank 152 is enclosed and has incorporated therewith suitable agitators 154 and 156 which gently blend the liquids fed thereto so as to eliminate splashing and any accompanying incorporation of air into the surface of the juice which might otherwise occur should the liquids be sprayed into the blend tank as has been customary in the juice concentrate industry. Accordingly, juice concentrate pipe 43A and cut-back juice supply pipe 153 as well as line 150 empty below the surface of liquids in the blend tank, and preferably at the bottom of the blend tank, 152 thereby eliminating splashing and accompanying air incorporation. Though it has not been found necessary to purge the headspace of the blend tank of oxygen it may be desirable to do so in the manner shown by the sweeping of nitrogen gas through the blend tank. Although it is a feature of the oily-watery fraction that it provides most of the balanced avor requirements for enhancement of a juice concentrate it may bc desirable for some applications to employ single strength fresh juice (that is cutback juice) in combination with the juice concentrate. When cut-back juice is employed, it is preferred that it be treated in the stripping column 160 where nitrogen gas is fed at a suiiicient rate to remove oxygen and carbon dioxide from the cut-back juice. The nitrogen stripped cut-back juice is then in a condition for blending with the other juice constituents.

The blended substantially oxygen-free juice in blending tank 152 is conducted by line 162 to a can-filling machine ld the juice in which may also be protected by nitrogen purging. The cans are thereafter delivered to a can-closing machine 166 and passed to a freezer as at 168. During the can-sealing operation nitrogen may be introduced into the headspace in the can in order to assure an inert atmosphere, although the can-sealing operation may be carried out under normal conditions without materially increasing the oxygen content of the final product. Indeed, it is an advantage of the present invention that by reason of the manner in which the various juice concentrate fractions are blended, nitrogen blanketing of the blend tanks, the can-lling machine as well as the canclosing machine can be substantially eliminated; it having been found that the elimination of splashing under pressure in the blend tank and the employment of high capacity, low impeller speed pumps avoids the introduction of air into the juice concentrate.

Where employed herein and in the accompanying claims the oxygen level specified may be determined in accordance with the following procedure:

A measured sample of the final juice concentrate or liquid to be tested is introduced into a container, such as the type commonly known as a desorbing bulb, which is partially lled with mercury to a desired level. The pressure in the container is slightly below atmospheric pressure at the time the sample is introduced. Either a measured amount of liquid is introduced into the container or the amount of liquid in the sample added may be determined by measuring the diiference in weight (or it? volume) of the liquid before and after the sample is taken.

The liquid level in the container is then lowered causing further evacuation of the space above the liquid. The lowered pressure results in the evolution of gases which occupy the evacuated space. The liquid level in the container is repeatedly raised and lowered in order to insure that all of the gas in the sample is removed. After the cessation of gas evolution, the liquid level in the container is raised so as to compress the liberated gases which are transferred to a gas burette. Upon completion of the transferral the pressure in the burette is adjusted to atmospheric conditions and the volume of gas is measured.

A small amount of 50 percent potassium hydroxide solution is added to the burette to absorb the carbon dioxide in the burette. The pressure in the burette is readjusted to atmospheric conditions and the volume of the gas therein is measured. The decrease in volume from the original measurement represents the total amount of carbon dioxide originally dissolved in the sample. Then, a small amount of alkaline pyrogallol solution [two volumes of 33 percent pyrogallol and one volume of 50 percent potassium hydroxide] is added to the burette so as to absorb the oxygen therein. The pressure in the burette is readjusted to atmospheric conditions and the volume of gas is again measured. The decrease in volume from the last measurement represents the total amount of oxygen originally dissolved in the sample.

lf necessary, the oxygen volume measurement is converted to standard temperature and pressure (STP) by suitable temperature and barometric corrections, divided by the weight of the sample7 and multiplied by 100 to obtain the results as ml. of oxygen per gms. of the juice concentrate tested.

This ratio is for the speciiix Brix level of the juice concentrate from which the sample was taken. As discussed hereinbefore, the critical oxygen level described herein utilizes a juice concentrate having a Brix level of 42 Brix as a reference point. Should the Brix level of the juice concentrate from which the sample tested was taken be more or less than 42 Brix, suitable adjustments should be made to convert the last-named ratio to an equivalent ratio at a Brix level of 42 and thereby determine whether the oxygen level is at or below the critical level specified herein. It is, of course, understood that the above oxygen level testing procedure is only one of the many testing procedures which can be used to determine the oxygen level in the product.

The discovery that the high as Well as low boiling components of this oily-watery fraction are useful in enhancing a juice concentrate with a well rounded and complete flavor and aroma was to some extent unexpected since it had been previously believed that only the low boiling constituents were useful in this capacity and since the higher boiling constituents had been generally classed as a group making no desirable contribution to flavor and aroma and, indeed, detracting from over-all acceptability. One explanation for the acceptability of the oily-watery fraction recovered may be the presence therein among the high boiling constituents of sack oils believed by some early prior art workers to be derived from juice extracts of the citrus fruits. The oily-watery fraction may be added back directly to the concentrate or to so-called cutback juice, i.e., the fresh dilute juice to which concentrate has heretofore been added, to give the concentrates a natural ilavor. However, it is an advantage of the present oily-watery fraction that cut-back juice need not be employed in preparing suitably flavored finished concentrates and, indeed, it is a preferred practice not to employ cutback juice but to add the oily-watery fraction to juice concentrate. Collateral to this advantage, therefore, is the practicality of concentrating the juice to a lower density than that to which juice concentrate is normally reduced, the practice of adding cut-back juice is no longer necessary. Thus, orange juice concentrate produced in accordance with the present invention will have a Brix level of about 45 and will be adjusted to a Brix level of about 42 by addition of the oily-watery fraction, it being preterred that the oily-watery fraction constitute approximately by volume of the juice concentrate. By virtue of the reduction of the oxygen level to 0.02 mi. per 100 gms. of juice concentrate at the reference Brix level of 42 in the course of concentration of the citrus juice and by the avoidance of the need for cut-back juice which has a relatively high oxygen level, the flavorful juice concentrate is found to be surprisingly stable and the need for nitrogen sparging or other inert maintenance is eliminated.

It will be noted from the foregoing description that the heat of the compressed refrigerant gas is employed both (1) to boil the juice and separate therefrom desired volatiles containing flavor-producing constituents which boil at temperatures above and below that of water; and (2) to distill from the two-phase oily-watery mixture recovered by condensation a fraction containing said high and low boiling davor-producing constituents. It will also be noted that when the hot compressed refrigerant gas is brought into heat exchange relation with the juice and the juice condensate it surrenders its heat and-lquenes, whereafter it is recycled to a receiver and eventually may be used to condense either the volatiles recovered by boiling the juice or the desired flavor fraction recovered upon condensation. Advantageously, therefore, the flavor fraction of use is recovered as part of a cycle wherein the refrigerant gas is also employed to concentrate the juice. By repeatedly recirculating the refrigerant the latent heat of the refrigerant in a compressed condition may be utilized to supply heat for evaporation and the liqueed refrigerant may be employed to receive heat from vapors where a vapor condensate is to be recovered from the system.

it should be further noted that the flavor fraction of use eventually recovered will in the case of orange or other citrus juices appear somewhat milky but when allowed to settle will be seen to separate into a watery-phase superposed by an oily-phase. In practice all of the oilyphase or all of the watery-phase may not always be added back. As a consequence after a substantial portion of this oily-watery fraction is recovered that which is to be used will be separated from that which is not to be used such as by permitting the emulsion to settle in an elongated chamber and thereby separate into its respective phases so that the desired amount of each phase may then be conveniently added to the concentrate.

While the present invention has been described with particular reference to specific examples, it is not to be limited thereby, but reference is to be had to the appended claims for a definition of its scope.

What is claimed is:

1. A process of ortifying and stabilizing a citrus fruit juice with a specitic traction of volatile constituents Whose boiling points are above and below that of water, comprising separating the juice into a major concentrated juice portion and a minor volatile portion which contains said volatile davor-producing constituents and noncondensible gaseous constituents by subjecting the juice to a high vacuum concentration operation at a temperature less than 120 F., condensing a major proportion of the volatile flavor-producing constituents as a irst twophase oily-watery mixture and evacuating uncondensed volatile constituents and non-condensible gases as a minor proportion of the volatile portion, discarding said minor proportion of the Volatile portion, thereafter distilling a flavorful and aromatic mixture of said high and low boiling constituents from the resulting two-phase oily-watery mixture at a temperature below F. and an absolute pressure of less than 11/2 of mercury by causing a thin iilm of said two-phase oily-watery mixture to travel along a heat exchange surface and condensing a minor subfraction of said mixture, a major portion of said minor subfraction being a watery phase and a minor portion of said minor subtraction being an oily-phase, combining said minor subtraction with juice concentrate by creating a reservoir of said juice concentrate and incorporating said minor subfraction therein beneath the surface thereof without substantial agitation therein, passing the combination of said juice concentrate and minor subtraction to a container filling and closing operation through a substantially airtight system to preclude substantial introduction of air into the juice concentrate, the final oxygen content of the packaged product not exceeding 0.20 ml. per 100 gms. of the product at 42 Brix, and freezing the packaged product thus produced.

2. Process according to claim 1 wherein another portion of whole citrus juice is also combined with said reservoir by being introduced beneath the surface thereof to avoid splashing of the combined juice and juice concentrate, said added Whole citrus juice having been previously stripped of oxygen and carbon dioxide therein by sparging an inert gas therethrough,

3. Process according to claim 2 wherein said reservoir has an oxidizing atmosphere above the surface thereof.

References Cited in the tile of this patent UNITED STATES PATENTS 2,450,774 Zahn Oct. 5, 1948 2,513,813 Milleville July 4, 1950 2,625,505 Cross Jan. 13, 1953 2,911,308 Smith Nov. 3, 1959 

1. A PROCESS OF FORTIFYING AND STABILIZING A CIRTRUS FRUIT JUICE WITH A SPECIFIC FRACITON OF VOLATILE CONSTITUENTS WHOSE BROILING POINTS ARE ABOVE AND BELOW THAT OF WATER, COMPRISING SEPARATING THE JUICE INTO A MAJOR CONCENTRATED JUICE PORTION AND A MINOR VOLATILE PROTIN WHICH CONTAINS SAID VOLATILE FLAVOR-PRODUCING CONSTITUENTS AND NONCONDENSIBLE GASEOUS CONSTIUENTS BY SUBJECTING THE JUICE TO A HIGH VACUUM CONCENTRATION OPERATION AT A TEMPERATURE LESS THAN 120*C., CONDENSING A MAJOR PROPORTION OF THE VOLTAILE FLAVOR-PRODUCING CONSTITUENTS AS A FIRST TWOPHASE OILY-WATERY MIXTURE AND EVACUATING UNCONDENSED VOLATILE CONSTITUENTS AND NON-CONDENSIBLE GASES AS A MINOR PROPORTION OF THE VOLATILE PORTION, DISCARDING SAID MINOR PROPORTIN OF THE VOLATILE PORTION, THEREAFTER DISTILLING A FLAVORFUL AND AROMATIC MIXTURE OF SAID HIGH AND LOW BOILING CONSTITUENTS FROM THE RESULTING TWO-PHASE OILY-WATERY MIXTURE AT A TEMPERATURE BELOW 100*F. AND AN ABSOLUTE PRESSURE OF LESS THAN 1 1/2" OF MERCURY BY CAUSING A THIN FILM OF SAID TWO-PHASE OILY-WATERY MIXTURE TO TRAVEL ALONG 